A common insecticide really does contribute to the death of bees, according to a large-scale field study. This helps set to rest some of the controversy over the use of the chemicals.
The type of insecticide in question, called neonicotinoids, is often used to coat crops. In a study published today in the journal Science, researchers grew rapeseed in 33 sites across Germany, the United Kingdom, and Hungary. They coated the crop with neonicotinoids, introduced various bee species to the area, and monitored the health of the colonies compared to control groups. (These chemicals were made by the companies Bayer CropScience and Syngenta, which helped fund the study.) The bees who lived near the plants treated with neonicotinoids had more trouble surviving the winter.
Before now, we were still unsure just how harmful these particular insecticides were. In 2013, the European Union banned the chemicals due to concerns that they were killing bees, which are crucial for agriculture. Currently, bee populations are falling worldwide. Still, the ban has been controversial, with some critics saying that the simulations in earlier studies were unrealistic.
Today’s study is one of the first large-scale field reports. Honeybees in the United Kingdom had difficulty surviving to begin with, but survival was lowest near crops treated with neonicotinoids the year before. Similarly, in Hungary, colony numbers fell by 24 percent by following spring. However, there was no effect in Germany.
The authors suggest that the different results may be because of the different climates naturally found in the three countries. Hives in Germany are usually larger to begin with and closer to a wider range of flowers than those in the UK and Hungary. Overall, though, because this was a field study that mimics real-world conditions, the study goes a long way toward settling the debate on these chemicals, even if the news isn’t good.